1. Field of the Invention
The present invention relates generally to the field of industrial power plant furnace and boiler systems and, in particular, to a new and useful apparatus and method for reducing or removing carbon dioxide (CO2) and sulfur oxides (SO2 and SO3) from flue gases exiting such systems.
2. Description of the Related Art
Processes and devices for removing specific contaminant gases such as carbon dioxide or sulfur oxides from power plant systems have generally been known for many years, including open spray towers, packed towers, and tray towers. Known apparatus for separating these gases from the flue gas streams exiting the furnace systems requires first removing the sulfur oxides at a first location and then removing the carbon dioxide gases at a second location. The separation of steps is necessary because of undesirable reactions between the components of the different separation and removal systems.
Commonly, amines such as monoethanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA) are used to capture carbon dioxide from flue gases exhausting from fossil fuel power systems. Unfortunately, sulfur dioxide (SO2) degrades these amines and inhibits the carbon dioxide removal. This is why carbon dioxide and sulfur oxide separation in current systems takes place in two separate steps in two different vessels.
Articles discussing known separation techniques include: Albanese, A. S. and M. Steinberg, xe2x80x9cEnvironmental Control Technology for Atmospheric Carbon Dioxidexe2x80x94Final Report,xe2x80x9d Brookhaven National Laboratory Report BNL 51116, UC-11, for US DOE, September 1979; Chadwick, J. L., xe2x80x9cAcid Gas Removal,xe2x80x9d SRI International Report No. 24 for Energy Technology Economics Program, July 1981; Pauley, C. R., xe2x80x9cCO2 Recovery from Flue Gas,xe2x80x9d Chemical Engineering Progress, May 1984; Miller, D. B., T. J. Soychak and D. M. Gosar, xe2x80x9cEconomics of Recovering CO2 from Exhaust Gases,xe2x80x9d Chemical Engineering Progress, October 1986; Cheng, H. C. and M. Steinberg, xe2x80x9cA Study on the Systematic Control of CO2 Emissions from Fossil Fuel Power Plants in the U.S.,xe2x80x9d Environmental Progress, Vol. 5, No. 4, November 1986; Hendriks, C., Carbon Dioxide Removal from Coal-Fired Power Plants, Kluwer Academic Publishers, Dordrecht, Netherlands 1994; Leci, C. L., xe2x80x9cFinancial Implications on Power Generation Costs Resulting from the Parasitic Effect of CO2 Capture Using Liquid Scrubbing Technology from Power Station Flue Gases,xe2x80x9d Energy Conversion Management, Vol. 37, Nos. 6-8, 1996; and Herzog, H., E. Drake and E. Adams, xe2x80x9cCO2 Capture, Reuse, and Storage Technologies for Mitigating Global Climate Change,xe2x80x9d White Paper Final Report, MIT Energy Laboratory for US DOE, January 1997.
It is clear that there is a need to separate both carbon dioxide and sulfur dioxides from flue gases, as expressed in several of the articles. However, a combined unit which can effectively separate both types of contaminants from flue gas flows has not been available.
It is an object of the present invention to provide a single vessel for capturing both carbon dioxide and sulfur oxides from power plant flue gases.
It is a further object of the invention to provide a separation vessel which combines the two gas separation processes without interference of one process with the other.
It is a further object of the invention to provide a simple, mechanical separator between the gas separation processes within the vessel.
Accordingly, a combined removal system for separating carbon dioxide and sulfur oxide gases from furnace flue gases is provided within a single vessel having two chambers. The chambers are separated by a series of baffles and drains. Additionally, a series of droplet separators, also known as mist eliminators or moisture separators, may be used as a further separation means. The primary chamber contains reagents and a delivery system for removing sulfur oxides (SO2 and SO3) from the flue gases. The secondary chamber has reagents for removing carbon dioxide (CO2) from the flue gases. The baffles and drains permit the flue gases to pass from the primary chamber into the secondary chamber, while collecting an amine solution used to trap carbon dioxide. Alternatively, the primary and secondary chambers may be separated by a horizontal segment or a combination of horizontal and vertical sections.
The use of baffle systems for solid particulate removal and collection of condensate from gas flows in various sections of a furnace or boiler is known. However, the present inventor is not aware of baffle systems being used to separate chambers of a single vessel gas separation unit of the type described herein; i.e., a single unit containing means for separating both gases from the flue gas flow.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.